'I think I've found the right cross,' he announced as the call connected. Stokes came over frowning and mouthing the word 'Where?'

He pointed at the ground. Stokes looked down, then his eyeline returned to the Holbein painting. The broad violet carpet runners laid across the white marble floor bisected one another directly in front of the painting, forming one gigantic ianthine crucifix, with two smaller ones on either side.

'Well I'll be damned,' said Stokes.

'Where does the top of it point?' asked Masters.

Vince shone the torch up on a Pre-Raphaelite painting of two lovers standing beside a tree.

'That's not normally there,' Stokes explained. 'It belongs in Birmingham City Art Gallery. It's on loan.'

'What is it?' asked Vince.

'Not to my taste at all,' said Stokes. 'All that preachy Victorian stuff is like stuffing yourself with iced buns, too sickly. I prefer something more robust. Tintoretto's more my style -'

'The painting, man, what is it?' Masters fairly shouted over the line.

While Vince stretched the telephone cord as far as it would reach, Stokes peered close at the painting with his torch held high. 'It's called The Long Engagement, by Arthur Hughes.'

'I've got it,' cried Maggie, proudly holding the picture up for everyone to see.

'Well, what does it say?'

'It was originally called Orlando in the Forest of Arden. The artist replaced the central figure with lovers after the picture was rejected by the Royal Academy.' She read aloud. '"The woman waits for her lover to marry her, even though she has been waiting so long that ivy has grown over her name, carved into the tree's bark." Amy,' she said, closing the book. The girl's name is Amy.'

'I REALLY have to make a phone call,' said Pam, shifting uncomfortably in the armchair where Xavier Stevens had unceremoniously dumped her. 'They have no right to keep me here like this.'

'Sebastian doesn't see it like that,' said Barwick apologetically. 'I can't untie your hands again. He'd be furious with both of us.'

'One call, Horace. I promise I won't get you into trouble. It's not as if I'm going to ring the police or anything.' She wriggled and grimaced, pantomiming pain. 'At least find some proper rope.'

She had turned on the waterworks and admitted to Xavier Stevens that the other disk containing Vince's manuscript was carefully hidden in the bottom drawer of her office desk, failing to mention that, having suffered a series of break-ins, the estate agency was abnormally well alarmed, and the disk wasn't there anyway. She prayed he would get caught astride the window ledge in a blaze of light, but doubted her luck would hold out that far; if he didn't, he might well return in a less amenable frame of mind.

Vince had hand-delivered one of the disks to Esther Goldstone a few days ago, and, she knew, had planned to give Louie the other. She had no idea where it had gone from there, but knowing Louie, he had probably left it in the pub. At least she was holding her own against these arrogant young men, standing up to them. She could be just as bloody-minded as they were. She felt that the lessons she had learned in her most recent business management course ('Hidden Persuasion at the Negotiating Table: The Art of Striking a Deal') were starting to pay off, and decided to put more of them into practice. Mark your man, they taught her, mark and mirror him. 'Now listen to me, Horace,' she wheedled, making eyes at the alarmed Barwick, 'come and sit over here beside me. I have an interesting proposition for you.'

The envelope was sellotaped to the base of the painting's frame. George Stokes had just finished easing it free when his wristwatch started emitting a reedy beep.

'That's it, lad, our time's up. We're too late. The alarm sensors are going back on right throughout the building. I don't know how I'm going to get you out of here now.' He shone his torch back along the corridor.

'What happens if we don't make it?' asked Vince.

'Every light in and around this place goes on, and sirens start up the likes of which won't have been heard in the capital since the Second World War,' he explained grimly. 'Make for that doorway over there. Stay off the carpet, but don't go any nearer than five feet to the wall. Don't touch anything.'

Thirty years of prowling the museum had caused the custodian to develop a delicate, silent run that made him appear to move on invisible wires. He sped through each eerie sepulchre like a tardy ghost. Vince could see thin pencil-beams of light flicking on all around them at a height of about eighteen inches from the floor. The sparkling red latticework was like a computerised spiderweb. Breaking any one of the gossamer lines would be enough to trip the entire alarm system.

A quadrant of beams pulsed on at his feet, forcing him to slow and step between them. 'Christ,' he whispered, 'they're everywhere.'

He was about to run through the archway leading to the main entrance when a row of beams appeared like a glittering ladder across the opening. Dropping to his knees and sliding the last few feet, he was able to avoid touching them by a matter of centimetres.

They reached the hall through which Vince had entered, and Stokes dived behind the reception desk just as the last of the override switches in the steel alarm box switched itself back on.

He looked up at Vince through a sweating bushy brow. 'That was too bloody close for comfort, lad,' he panted, pulling Vince towards a small side door. 'Well, you've got your precious envelope. Arthur Bryant has used up his last favour with me. I'm going back upstairs to fabricate some story for Albert. If you get into any further difficulties tonight you're on your own, understand?'

Vince clutched the unopened letter in his hand and looked out across Trafalgar Square. He was relieved to be out of the gallery without tripping the alarms. The rain had momentarily eased, and the roads were almost empty. An odd, contemplative stillness filled the air, as if the goddess of the city had momentarily fallen asleep.

Vince dug the phone from his jacket and rang Pam, but her answering machine switched itself on. The message she had left was a week old. He wondered if Louie had returned yet. It was unlikely, but worth a try. Vince punched out his number and waited, only to find himself connected to another answering machine. He gave the recording device his present location and Harold Masters' number before ringing off. A call to Esther connected him to a third tape machine. This time he hung up.

Where were all his friends? He had never felt so completely alone. His only link to the city's warm-and-normal interior world was via the lifeline to Harold Masters. He felt like chucking in the whole thing. What was the point of continuing, anyway? Let them bury the damned book, let them shut him up and anyone else that got in their way, what difference did it really make? He could find something else to write about for Esther. If they were that clever and all-powerful, they probably possessed both copies of the manuscript by now. He should have put them somewhere safer instead of placing Esther and Louie at risk.

He was exhausted. His arms and legs were turning into dead timber. He had twisted his right knee in the gallery. If he abandoned the game now and threw away the League's damned envelope, just turned on his boot-heel and caught the first night bus home, what would Sebastian do? Kill him? Where the hell were the League anyway? Did they really have nothing better to do than watch him stumbling blindly through the night? He wanted to be back in Betty's inviting arms, not stuck here in the city he had only thought he loved. He looked across the wet road to St Martin in the Fields, at the blank eyes of the security cameras peering down from the eaves like so many metallic ravens. The question nagged at him; what would they do if he stopped?